# SSL certificate

URL: https://tnb-tech.com/en/glossary/ssl-certificate/

## What is an SSL certificate?

An SSL certificate is the electronic document that proves which domain a site belongs to and lets the connection run encrypted over HTTPS, with the padlock in the address bar. A certificate authority issues it for a fixed period, and it has to be renewed before it expires. It encrypts what passes between browser and server, so passwords and submitted forms cannot be read on the way.

**Example**

A company site’s certificate expires on a Saturday morning. From that moment every visitor meets a full-page warning that the connection is not private, with a button they have to click deliberately to go on. Most people do not go on. The form is not filled in, and in the analytics it looks like a sudden drop in traffic rather than a technical fault.

The fix takes minutes; the loss is in the hours before anyone notices. So a certificate is either renewed automatically or watched as a date — not discovered by a customer ringing to ask why their browser is stopping them. Who issued the certificate on a domain, and how long it runs, takes seconds to read in the domain check.

The types, briefly. Domain validation (DV) proves only that you control the domain and is issued automatically; for most sites that is enough. Organisation validation (OV) and extended validation (EV) add checks on the company itself; browsers stopped showing them differently years ago, so the difference is in what the other side trusts, not in the interface. A wildcard certificate covers subdomains as well.

Validity is being shortened on an industry schedule: since 15 March 2026 a new certificate lasts at most 200 days, from 15 March 2027 that becomes 100, and from 15 March 2029 it becomes 47. Renewing by hand stops being practical; issuing has to be automatic.

**Why it matters for a business**

HTTPS is not an extra. Browsers mark pages without it as not secure and warn inside password and payment fields. Google has used HTTPS as a ranking signal since 2014. And a form collecting personal data over an unencrypted connection is hard to defend against the requirement to protect that data by appropriate technical means.

A certificate protects the route, not the site. It stops nothing about a stolen password, a vulnerable module or malicious code in a theme. The name is historical too: SSL is the protocol TLS replaced, but the certificates are still called SSL.

Renewing certificates runs together with platform and module updates in monthly website maintenance.

**What to ask**

- Who issues the certificate, and does it renew automatically?
- Who receives the warning thirty days before it expires?
- Does http redirect to https, and is HSTS switched on?
- Is there mixed content — images or scripts still loaded over http — removing the padlock?
- Does it cover the www variant and any subdomains you use?
- What happens if it expires on a Saturday: who is called, and how fast is it fixed?

- Services: [Website maintenance](https://tnb-tech.com/en/services/website-maintenance/)
- Glossary: https://tnb-tech.com/en/glossary/